Adhesive for silicone rubber lining materials

ABSTRACT

An adhesive for silicone rubber lining materials, for adhering a silicone rubber lining material and a (meth)acrylic resin denture base together, comprising (a) 100 parts by weight of an organic solvent, (b) 0.1 to 20 parts by weight of a (meth)acrylic polymer modified with a siloxane having a functional group reactive in the hydrosilylation reaction; and (c) 0.1 to 20 parts by weight of a polymer of a (meth)acrylic acid alkyl ester represented by the following formula, CH 2 ═C(X)—COOR, wherein X is a hydrogen atom or a methyl group, and R is an alkyl group having 1 to 6 carbon atoms. This adhesive adheres the silicone rubber lining material and the (meth)acrylic resin denture base together very strongly. The adhering force is favorably maintained not only in the initial period but also for extended periods of time, offering excellent durability of adhesion. The initial adhering force and the durability of adhesion are also exhibited even by using a halogen-free organic solvent.

TECHNICAL FIELD

The present invention relates to an adhesive for lining materials foradhering a silicone rubber lining material with a denture base made of a(meth)acrylic resin. More specifically, the invention relates to anadhesive for silicone rubber lining materials, which can be suitablyused when a halogen-free organic solvent is used as an organic solvent.

The invention further relates to a kit for lining a denture base made ofa (meth)acrylic resin, comprising the above adhesive for the liningmaterials and a settable composition for the silicone rubber liningmaterials, and to a method of adhering the silicone rubber liningmaterial and a (meth)acrylic denture base by using the adhesive for thelining materials.

BACKGROUND ART

A large proportion of patients who must be fitted with a denture and,particularly, with a full denture are aged persons. In general, further,the alveolar ridge shows such a large bone absorption that an increasedforce of occlusion must be born per a unit area. The alveolar ridgemucosa, too, becomes thin due to senile atrophy. Therefore, the shockdue to occlusion and masticatory pressure is not relaxed but is directlytransmitted to the alveolar bone. As a result, a thin mucosa sandwichedbetween the hard resin denture base and the hard alveolar bone issqueezed and gets scarred after every occlusion, and produces a pain.

In such a difficult case of disease, good results are not obtained forstably maintaining and supporting the denture even if the denture baseis produced by using a commonly used (meth)acrylic resin only. Namely,it is necessary to line the surface of the denture base mucosa with amaterial having a suitable degree of elasticity, to compensate the lostviscoelasticity of the residual ridge mocusa and to impart cushioningproperty for relaxing the shock at the time of occlusion.

There has been favorably used a silicone rubber lining material of theroom temperature vulcanizing type that cures at a temperature of up to50° C. However, the silicone rubber lining material poorly adheres tothe (meth)acrylic resin which is the denture base. Therefore, there havebeen developed several adhesives for adhering the (meth)acrylic resinwhich is the denture base with the silicone rubber material which is thelining material, and there has been known the one obtained by dissolvinga particular acrylic copolymer having a silyl group in a suitablevolatile organic solvent.

For example, there have been developed an acrylic copolymer using analkyl (meth)acrylate and a (meth)acrylic acid dimethyl vinyl silylalkylester (Japanese Unexamined Patent Publication (Kokai) No. 43209/1990)and an acrylic copolymer using an alkyl (meth)acrylate and a(meth)acrylic acid dimethyl hydrogensilylalkyl ester (JapaneseUnexamined Patent Publication (Kokai) No. 68007/1992).

They are used by applying soluble solvent solutions of the above resinsonto the (meth)acrylic resin of the denture base followed by drying and,then, applying a room temperature vulcanizing (setting through thehydrosilylation reaction) silicone paste which is a dental liningmaterial. During the setting and/or after the setting, however, theymust be heated at about 80° C. for 20 to 30 minutes or longer toaccomplish a sufficient degree of adhesion.

There have further been developed acrylic random copolymers modifiedwith a silicone having a polyorganosiloxane group with an SiH reactionpoint on a side chain thereof (Japanese Patents Nos. 3105733 and3107702). The adhesives using these particular acrylic random copolymersare useful being capable of considerably strongly adhering the acrylicresin which is the denture base and the silicone rubber material whichis the lining material together at low temperatures of from about 20 toabout 30° C. within several minutes.

However, it has been desired to further improve the adheringperformance.

As the organic solvent for dissolving the above silicone-modifiedacrylic copolymers, in particular, there has been used ahalogen-containing organic solvent and, chiefly, methylene chloride. Useof the above organic solvent helps exhibit excellent adheringperformance.

In recent years, however, the halogen-containing organic solvents havebeen suspected of causing environmental disruption and toxicity. Thoughthe truth has not yet been clarified, it is desired to avoid the use ofhalogen-containing organic solvents even in the dental materials.

Therefore, the adhesive is now using a halogen-free organic solvent suchas ethyl acetate or ethyl methyl ketone to substitute for thehalogen-containing organic solvent. In this case, the obtained adhesiveexhibits excellent adhering force nearly equal to the halogen-containingorganic solvent in the initial stage of adhesion accompanied, however,by such a defect that the adhering force greatly decreases with thepassage of time lacking durability in the adhering force (durability ofadhesion).

As the adhesive for the lining materials, further, there has furtherbeen known the one comprising the above silicone-modified acryliccopolymer and an organic solvent of a polymer of a particular(meth)acrylic acid ester having a carboxyl group for adhering thesilicone rubber lining material and the metallic denture base (JapaneseUnexamined Patent Publication (Kokai) No. 25292/1993). The aboveadhesive, however, is not still satisfactory for the use of adhesionsince its adhering force to the (meth)acrylic resin denture base is notsatisfactory.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an adhesive forsilicone rubber lining materials, capable of firmly adhering the(meth)acrylic resin and the silicone rubber lining material together,and exhibiting excellent durability of adhesion.

Another object of the present invention is to provide an adhesive forsilicone rubber lining materials, favorably exhibiting the aboveexcellent adhering performance even when the organic solvent that isused is a halogen-free organic solvent.

A further object of the present invention is to provide a kit for lininga (meth)acrylic resin denture base, comprising the above adhesive forlining materials exhibiting excellent adhering performance and asettable composition for the silicone rubber lining materials.

A still further object of the present invention is to provide a methodof adhering a silicone rubber lining material and a (meth)acrylic resindenture base together by using the above adhesive for the liningmaterials exhibiting excellent adhering performance.

According to the present invention, there is provided an adhesive forsilicone rubber lining materials, for adhering a silicone rubber liningmaterial and a (meth)acrylic resin denture base together, comprising:

(a) 100 parts by weight of an organic solvent;

(b) 0.1 to 20 parts by weight of a (meth)acrylic polymer modified with asiloxane having a functional group reactive in the hydrosilylationreaction (hereinafter abbreviated as reactive siloxane-modified(meth)acrylic polymer); and

(c) 0.1 to 20 parts by weight of a polymer of a (meth)acrylic acid alkylester (hereinafter abbreviated as (meth)acrylic acid lower alkyl esterpolymer) represented by the following formula,CH₂═C(X)—COOR

wherein X is a hydrogen atom or a methyl group, and

R is an alkyl group having 1 to 6 carbon atoms.

According to the present invention, there is further provided a kit forlining a (meth)acrylic resin denture base comprising (I) a settingcomposition for silicone rubber lining materials, an (II) the adhesivefor the lining materials.

According to the present invention, there is further provided a methodof adhering a silicone rubber lining material and a (meth)acrylic resindenture base together by adhering the silicone rubber lining materialwith the (meth)acrylic resin denture base together by using the adhesivefor the lining materials.

BEST MODE FOR CARRYING OUT THE INVENTION Adhesive for the LiningMaterials

An adhesive for silicone rubber lining materials of the presentinvention is obtained by blending (a) an organic solvent with (b) areactive siloxane-modified (meth)acrylic polymer and (c) a (meth)acrylicacid lower alkyl ester polymer.

This adhesive is capable of very strongly adhering the silicone rubberlining material and the (meth)acrylic resin denture base together, theadhering force being favorably maintained not only in the initial periodonly but also over an extended period of time, showing excellentdurability of adhesion. Such a durability of adhesion is exhibitedparticularly by being blended with a (meth)acrylic acid lower alkylester polymer which is the component (c). That is, when not beingblended with the component (c), a considerably good initial adheringforce is obtained, which, however, does not last for extended periods oftime, and the durability of adhesion decreases greatly.

Component (c):

The (meth)acrylic acid lower alkyl ester polymer which is the component(c) that is characteristic of the present invention is a polymer of a(meth)acrylic acid alkyl ester represented by the following formula,CH₂═C(X)—COOR

wherein X is a hydrogen atom or a methyl group, and

R is an alkyl group having 1 to 6 carbon atoms, offering such advantagesthat it dissolves well in an organic solvent, can be favorably appliedas a homogeneous solution, exhibits good affinity to the (meth)acrylicresin of the denture base that is to be adhered, and helps increase theadhering strength to the resin as described above.

When the number of carbon atoms of the alkyl group (R) in the aboveformula is not smaller than 6, even the polymer of the (meth)acrylicacid alkyl ester dissolves poorly in the organic solvent, and exhibitsdecreased affinity to the (meth)acrylic resin which is the denture baseto be adhered, causing a decrease in the durability of adhesion.Further, when a hydrophilic group such as carboxyl group is bonded as asubstituent to the alkyl group (R), affinity decreases relative to thehighly hydrophobic silicone rubber lining material that is to beadhered.

In the (meth)acrylic acid lower alkyl ester polymer which is thecomponent (c) used in the invention, the alkyl group (R) in the formulahas 1 to 6 carbon atoms, and is an unsubstituted alkyl group such asmethyl group, ethyl group, propyl group, butyl group, pentyl group orhexyl group. Concrete examples of the polymer of the (meth)acrylic acidalkyl ester having such an alkyl group (R) include homopolymers such asmethyl acrylate, methyl methacrylate (MMA), ethyl acrylate, ethylmethacrylate (EMA), propyl acrylate, propyl methacrylate, butylacrylate, butyl methacrylate, hexyl acrylate and hexyl methacrylate, orcopolymers thereof.

The (meth)acrylic acid lower alkyl ester polymer may further have anyother copolymerizable monomer unit in small amounts in a range in whichthe effect of the invention is not impaired, which is generally notlarger than 3% by mol and, preferably, not larger than 1% by mol. Assuch other copolymerizable monomers, there can be exemplifiedacrylonitrile, acrylamide, styrene, methyl styrene and α-methyl styrene.

Among the above (meth)acrylic acid lower alkyl ester polymers of theinvention, it is desired to use a polymer of the (meth)acrylic acidalkyl ester having the alkyl group (R) with 1 to 4 carbon atoms and;most desirably, to use a polymer of the (meth)acrylic acid alkyl esterhaving the alkyl group (R) with 1 to 2 carbon atoms, such as a copolymerof methyl acrylate and ethyl acrylate, and a homopolymer of methylmethacrylate (MMA) and ethyl methacrylate (EMA).

Though there is no particular limitation, it is desired that the(meth)acrylic acid lower alkyl ester polymer (c) has a weight-averagemolecular weight in a range of from 10,000 to 2,000,000 and,particularly, from 100,000 to 1,000,000 from the standpoint ofmaintaining highly dissolving property in the organic solvent anduniform applicability of the adhesive.

The (meth)acrylic acid lower alkyl ester polymer is, in many cases,obtained by polymerizing a starting monomer in the presence of aperoxide. From the standpoint of preservation stability of the adhesiveof the present invention, however, it is desired that the amount of theresidual peroxide is not larger than 1.0% by weight.

In the present invention, the (meth)acrylic acid lower alkyl esterpolymer which is the component (c) is blended in an amount of from 0.1to 20 parts by weight per 100 parts by weight of the organic solventwhich is the component (a). When the (meth)acrylic acid lower alkylester polymer is blended in an amount of smaller than 0.1 part byweight, durability of adhesion is not obtained to a sufficient degree.When the blending amount exceeds 20 parts by weight, on the other hand,the adhesive layer becomes too thick resulting in a decrease in thestrength of adhesion. It is particularly desired that the (meth)acrylicacid lower alkyl ester polymer is blended in an amount of from 0.1 to 10parts by weight for accomplishing a low viscosity and good operability.

Component (b):

In the present invention, the reactive siloxane-modified (meth)acrylicpolymer which is the component (b) comprises a homopolymer or acopolymer of a derivative of the (meth)acrylic acid ((meth)acrylic acidmonomer) to which is bonded, as a side chain, a siloxane group having afunctional group reactive in the hydrosilylation reaction.

As the functional group reactive in the hydrosilylation reaction, therecan be exemplified a functional group having an unsaturated carbondouble bond at a terminal or an Si—H group. Among them, desired examplesinclude vinyl group, allyl group and Si—H group. From the standpoint ofreactivity, further, the Si—H group is more desired.

The siloxane group having the above reactive functional group is the onehaving at least one silicon-oxygen-silicon bond and is, usually, anorganosiloxane group. It is desired that the siloxane group has theaverage number of repeating units of siloxane units such asorganomonosiloxane groups or organodisiloxane groups of from 1 to 200and, particularly, from 10 to 100.

In the reactive siloxane-modified (meth)acrylic polymer which is thecomponent (b), it is desired that the siloxane group having a reactivefunctional group exists in an amount in a range of from 0.1 to 90% bymole and, preferably, from 1 to 50% by mol of the (meth)acrylic acidmonomer unit that constitutes the (meth)acrylic polymer. It is furtherdesired that the number of the reactive functional groups exiting in aunit of siloxane groups is from 1 to 100 and, preferably, from 3 to 100.

Concrete examples of the reactive siloxane-modified (meth)acrylicpolymer include (meth)acrylic copolymers having a structural unit (α)represented by the following formula (1), having a structural unit (β)represented by the following formulas (2) and/or (2′), and having astructural unit (γ) represented by the following formula (3),

In the above formulas (1), (2), (2′) and (3):

R¹, R² and R¹³ are a hydrogen atom, a methyl group or an ethyl group;

R³ is an alkyl group having 1 to 13 carbon atoms or an aryl group having6 to 14 carbon atoms;

R⁴ to R¹⁰ and R¹⁵ to R²¹ are an alkyl group having 1 to 6 carbon atomsor an aryl group having 6 to 14 carbon atoms;

R¹¹, R¹² and R²² are a hydrogen atom, an alkyl group having 1 to 6carbon atoms or an aryl group having 6 to 14 carbon atoms;

R¹⁴ is an unsaturated hydrocarbon group having 2 to 20 carbon atoms,which may have an ether bond or an ester bond in the main chain thereof;

A is a divalent hydrocarbon group having 2 to 20 carbon atoms, which mayhave an ether bond or an ester bond in the main chain thereof;

c and d are average number of repeating units, c being a number of from1 to 100 and d being a number of from 0 to 100, and wherein 10≦c+d≦100and 0≦d/c≦10.

In the above structural units (α), (β) and (γ), R¹, R² and R¹³ in theformulas (1), (2), (2′) and (3) are those selected from a hydrogen atom,a methyl group and an ethyl group, and are, desirably, hydrogen atoms ormethyl groups from the standpoint of easily obtaining the raw materials,easy synthesis of a copolymer and, particularly, copolymerizationreactivity of the starting monomer {(meth)acrylate compound}.

R³ is an alkyl group having 1 to 13 carbon atoms, such as methyl group,ethyl group, n-propyl group, n-hexyl group, cyclohexyl group, n-octylgroup or tridecyl group, or an aryl group having 6 to 14 carbon atoms,such as phenyl group, benzyl group or naphthyl group, and is, mostdesirably, a lower alkyl group having not more than 3 carbon atoms, suchas methyl group, ethyl group or n-propyl group.

R⁴ to R¹⁰ and R¹⁵ to R²¹ are each an alkyl group having 1 to 6 carbonatoms, such as methyl group, ethyl group, n-propyl group or n-hexylgroup, or an aryl group having 6 to 14 carbon atoms, such as phenylgroup, benzyl group or naphthyl group, and is, desirably, a methyl groupor a phenyl group from the standpoint of easy availability and synthesisof an organo(poly)siloxane having an SiH reaction point which is astarting material for synthesis.

R¹¹, R¹² and R²² are a hydrogen atom, an alkyl group having 1 to 6carbon atoms or an aryl group having 6 to 14 carbon atoms. Examples ofthe alkyl group and aryl group may be the same as those represented byR⁴ to R¹⁰. From the standpoint of synthesis of the organo(poly)siloxanehaving an SiH reaction point, which is the starting material, easyavailability and reactivity of the obtained copolymer, however, it isdesired that these groups (R¹¹, R¹² and R²²) are methyl groups or phenylgroups.

Further, R¹⁴ is an unsaturated hydrocarbon group having 2 to 20 carbonatoms, such as vinyl group, allyl group, 1-butenyl group, 9-decenylgroup, 2-(2-(2-(2-propenyloxy)ethoxy)ethoxy)ethyl group,2-(3-butenoyloxy)ethyl group, or oleyl group.

A is a divalent hydrocarbon group having 2 to 20 carbon atoms, which mayhave an ether bond or an ester bond in the main chain thereof and is,desirably, a divalent hydrocarbon group having 3 to 10 carbon atoms,which may have an ether bond or an ester bond from the standpoint ofeasy synthesis. Concretely, there can be exemplified the followinghydrocarbon groups,

In the structural unit (β), c and d in the general formula (2) or (2′)represent average numbers of repeating units of siloxane in thestructural unit, and are selected from ranges that satisfy the followingformulas:1≦c≦1000≦d≦10010≦c+d≦1000≦d/c≦13

From the standpoint of reactivity of the adhesive in the presentinvention, it is desired to so select c that the SiH groups are presentin a number of not smaller than 3 on an average in one structural unit(β)

It is desired that the content of the structural units (α) in the(meth)acrylic copolymer used as the component (b) is in a range of from10 to 99.9% by mol and, particularly, from 50 to 99.9% by mol, thecontent of the structural units (β) is from 90 to 0.1% by mole and,particularly, from 50 to 0.1% by mol, and the content of the structuralunits (γ) is from 0 to 89.9% by mole and, particularly, from 0 to 49.9%by mol. So far as being expressed by the above general formulas, each ofthe structural units (α), (β) and (γ) may be constituted not only by theunits of a single kind but also by a plural kinds of units. When thecontent of the structural units (α) is smaller than the above range orwhen the contents of other structural units (β) and (γ) are larger thanthe above ranges, the ratio of the organo(poly)siloxane portionoccupying the copolymer becomes great as compared to the (meth)acrylicpolymer portion even when the molecular weight of theorgano(poly)siloxane group is decreased in the structural unit (β). As aresult, the adhesive poorly fits to the (meth)acrylic resin portion ofthe denture base and exhibits decreased adhering force. Further, whenthe content of the structural units (γ) is greater than the above range,unsaturated bonds existing in excess amounts impair the room temperaturevulcanizing reaction (hydrosilylation setting reaction) of the siliconerubber lining material that is to be adhered, and the adhesive does notwork to a sufficient degree. When the content of the structural units(β) is smaller than the above range, the ratio of theorgano(poly)siloxane portion decreases in the copolymer, and theadhesive poorly fits to the silicone rubber of the lining material andis not adhered to the silicone rubber with a sufficiently large force.

The organo(poly)siloxane portion stands for an SiO skeletal portionhaving an organic group, and means a portion defined by R⁴ to R¹² or R¹⁵to R²², c and d in the formulas (2) and (2′). Further, the (meth)acrylicpolymer portion stands for a poly(meth)acrylate skeletal portion otherthan the organo(poly)siloxane portion in the copolymer, and is definedby the number of the structural units (α), (β) and (γ), and by the ratioof the (meth)acrylic portion occupying the structural units (β).

It is desired that the (meth)acrylic copolymer used as the abovecomponent (b) has a weight-average molecular weight in a range of from5,000 to 1,000,000. The values c and d in the formulas (2) and/or (2′)representing the structural formula (β), the copolymer ratios of thestructural units (α), (β) and (γ), and the total number of polymers, aredetermined so that the weight-average molecular weight lies within theabove range. In the above copolymer, further, it is desired that theratio of the molecular weight of the organo(poly)siloxane portion andthe molecular weight of the (meth)acrylic polymer portion is selected tobe 1:0.1 to 2 from the standpoint of compatibility of the acrylic resinof the denture base with the silicone rubber portion, reactivity andeasy synthesis.

Described below are structures of structural units and the averagenumber of repeating units of representative reactive siloxane-modified(meth)acrylic polymers used as the component (b).

In the following formulas, Ph denotes a phenyl group.

These copolymers are usually in the form of white powdery solids.

The order of bonding the structural units and the siloxane units in theabove copolymers and the copolymers used in Examples and ComparativeExamples appearing later, can be selected quite arbitrarily, and thenumbers of repeating units in the structural formulas simply representthe structural units and average total amounts of the siloxane units.

There have heretofore been known the reactive siloxane-modified(meth)acrylic polymers comprising structural units (α) represented bythe formula (1), structural units (β) represented by the formulas (2)and/or (2′) and structural units (γ) represented by the formula (3),which can be produced in compliance with the methods taught in, forexample, Japanese Patents Nos. 3105733 and 3107702.

The reactive siloxane-modified (meth)acrylic polymer which is thecomponent (b) of the invention is blended in an amount of from 0.1 to 20parts by weight per 100 parts by weight of the organic solvent (a). Whenthe blending amount is smaller than 0.1 part by weight, the chemicalbonding between the polymer and the silicone rubber lining materialbased on the hydrosilylation reaction is not sufficient, and a strongadhering force is not obtained. When the blending amount exceeds 20parts by weight, the adhesive layer becomes so thick that the strengthof adhesion decreases. It is desired that the blending amount is from0.1 to 10 parts by weight to lower the viscosity and to obtain goodoperability.

Component (a):

There is no particular limitation on the organic solvent which is thecomponent (a) used in the present invention provided it is capable ofdissolving the polymers which are the components (b) and (c) describedabove, and it is allowable to use the halogen-containing organicsolvents such as methylene chloride and chloroform that have heretoforebeen used chiefly for the adhesive for silicone rubber lining materialsto a sufficient degree. In the present invention, however, it is desiredto use a halogen-free organic solvent.

In recent years, it has been desired to use a halogen-free organicsolvent as described above. However, the durability of adhesiondecreases to a large extent between the silicone rubber lining materialand the denture base. According to the present invention, on the otherhand, despite the halogen-free organic solvent is used, it is madepossible to effectively avoid a decrease in the durability of adhesion,which is a distinguished effect.

The halogen-free organic solvent is the one without having a halogensubstituent in the molecular skeleton thereof, and its examples includehydrocarbon compounds such as hexane, heptane and pentane; aromaticcompounds such as toluene and xylene; alcohol compounds such as ethanol,1-propanol, 2-propanol, 1-butanol and 2-butanol; ether compounds such asdiethyl ether, tetrahydrofurane and t-butyl methyl ether; ketonecompounds such as acetone, methyl ethyl ketone and methyl isobutylketone; and ester compounds such as ethyl formate, methyl acetate, ethylacetate, propyl acetate and isopropyl acetate.

According to the Council on Medicines No. 307, “Guideline of ResidualSolvent in the Medicines” issued to urban and rural prefectures from theMinistry of Health and Welfare in 1998, the toxicity of the solventsremaining in the medicines has been classified into three classes. Inthe present invention, too, it is desired that the organic solvent thatis used pertains to neither the Class 1 nor the Class 2 which are highlytoxic, from the standpoint of safety. Among the halogen-free organicsolvents, further, it is desired to use the one having a low boilingpoint and being volatile, since it dries quickly and is easy to handle.In particular, it is desired to use the one having a boiling point offrom 20 to 150° C.

Because of these reasons, it is particularly desired to use ethylacetate, acetone, ethyl methyl ketone or propyl acetate as the organicsolvent (a) that is used in the present invention, and it is mostdesired to use ethyl acetate to obtain durability of adhesion. Thehalogen-free organic solvents may be used in a single kind or in acombination of two or more kinds. When used being mixed together in twoor more kinds, it is desired that ethyl acetate is contained in anamount of not smaller than 50% by weight.

Other Components:

The adhesive of the present invention may contain additives such as acoloring agent, a perfume, etc. in addition to the above-mentionedcomponents (a) to (c) within a range in which they do not impair theeffect of the invention.

Preparation of the Adhesive:

The adhesive of the present invention can be easily prepared bydissolving the (meth)acrylic acid lower alkyl ester polymer (c) and thereactive siloxane-modified (meth)acrylic polymer (b) in the organicsolvent (a).

Method of Using the Adhesive

There is no particular limitation on the method of use so far as theabove adhesive of the present invention is used as an adhesive foradhering the denture base comprising chiefly the (meth)acrylic resin tothe silicone rubber lining material. According to a representativemethod of operation, the adhesive is applied onto the (meth)acrylicresin of the denture base, the solvent is vaporized, and a siliconepaste that sets through the hydrosilylation reaction, which is asilicone rubber lining material, is applied thereon so as to be set. Theadhesive adheres to the (meth)acrylic resin simultaneously with thesetting of the silicone paste that sets through the hydrosilylationreaction, and the adhesion is completed as the setting is completed.

Denture Base:

Here, the (meth)acrylic resin constituting the denture base is ahomopolymer or a copolymer of a (meth)acrylic acid ester. Concretelyspeaking, there can be preferably used a homopolymer or a copolymer of amethyl (meth)acrylate or an ethyl (meth)acrylate.

Silicone Rubber Lining Material:

The silicone rubber lining material comprises a polymer of a compound(organopolysiloxane) having a siloxane bond as a main chain and,usually, exhibits a good flexibility. As the lining material havingflexibility, there can be exemplified a soft lining material usedchiefly for repairing an ill-fitted denture and a tissue conditionerused chiefly for the therapy for a short period of time (one week toseveral weeks) until the damaged oral mucosa recovers to a healthystate. Both of them can be adhered by using the adhesive of the presentinvention.

As the silicone rubber settable composition for obtaining the siliconerubber lining material, any known material used for such applicationscan be used without any limitation. The polymerization for curing may beof the heated setting type, condensation type, addition type orultraviolet-ray curing type. It is, however, desired that thepolymerization is of the room temperature addition polymerization typesince it is capable of directly accomplishing the setting in the oralcavity of a patient without producing by by-products.

As the silicone rubber curable composition for the lining material ofthe room temperature addition polymerization type, there is desirablyused a curable composition that contains, comprising;

-   (i) an organopolysiloxane having at least two organic groups in the    molecules, the organic groups having a carbon-carbon unsaturated    bond at the terminal;-   (ii) an organohydrogenpolysiloxane having at least three SiH groups    in the molecules;-   (iii) a hydrosilylation catalyst; and-   (iv) a silicone resin filler material and/or a silica filler.

The settable composition for the silicone rubber lining material mayfurther contain (v) an organohydrogenpolysiloxane having one or two SiHgroups in the molecule to conduct the reaction. Upon being blended withthis component (v), the modulus of elasticity tends to decrease and itbecomes easy to adjust the viscoelasticity of the set body.

Details of the components used in the settable composition for siliconerubber lining materials have been disclosed in Japanese UnexaminedPatent Publications (Kokai) Nos. 226613/1998 and 79020/2001, and thesame components have also been used in the present invention.

For example, the organopolysiloxane which is the component (i)preferably used is represented by the following general formula,

-   -   wherein a is an integer of from 400 to 1500, b is an integer of        from 0 to 5, R²³ to R²⁹ are alkyl groups or aryl groups of the        same kind or different kinds, and R³⁰ is an organic group (e.g.,        a vinyl group or an allyl group)    -   having a carbon-carbon unsaturated bond.

Further, the organohydrogenpolysiloxane which is the component (ii)preferably used is represented by the following general formula,

-   -   wherein c is an integer of from 1 to 100, d is an integer of        from 3 to 50, R³¹ to R³⁷ are alkyl groups or aryl groups of the        same kind or different kinds, R³⁸ is an alkyl group, an aryl        group or a hydrogen atom, and R³⁹ is a hydrogen atom.

Further, the organohydrogenpolysiloxane which is the component (v)preferably used is represented by the following general formula,

wherein e is an integer of from 1 to 100, R⁴⁰ to R⁴⁵ are alkyl groups oraryl groups of the same kind or different kinds,

R⁴⁶ is an alkyl group, an aryl group or a hydrogen atom, and R⁴⁷ is ahydrogen atom.

As the hydrosilylation catalyst which is the component (iii), there canbe preferably used a platinum catalyst such as a chloroplatinic acid, analcohol-modified product thereof or a vinyl siloxane complex ofplatinum, or a similar rhodium catalyst.

It is desired that the silicone resin filler material used as thecomponent (iv) has an average particle size in a range of from 0.1 to100 μm and, particularly, from 0.1 to 20 μm. Concrete examples of thesilicone resin filler include polymethylsilsesquioxane, poly(0.1 to99.9% by mol of methyl+0.1 to 99.9% by mol of phenyl)silsesquioxne andpoly(99 to 99.9% by mol of methyl+0.1 to 1% by mol ofhydrogen)silsesqueoxane.

It is further desired that the silica filler used as the component (iv)has an average particle size of not larger than 10 μm and, particularly,in a range of from 0.001 to 1 μm. Concrete examples of the silica fillerinclude pulverized quartz, molten silica powder, wet silica and fumedsilica powder.

In the above curable composition, it is desired that the ratio ofamounts of the component (i) and the component (ii) is such that theratio of the total number of hydrogen atoms bonded to silicon atoms ofthe component (ii) to the total number of the carbon-carbon unsaturatedbonds at the terminal of the siloxane chain of the component (i) is from0.2 to 3.0 and, particularly, from 0.3 to 2.0.

When the component (v) is made present, further, it is desired that thecomponents (i), (ii) and (v) are so combined together that the ratio ofthe total number of hydrogen atoms bonded to silicon atoms of thecomponents (ii) and (v) to the total number of carbon-carbon unsaturatedbonds at the terminals of the component (i), is from 0.5 to 5.0 and,particularly, from 0.7 to 5.0.

There is no particular limitation on the amount of blending thecomponent (iii) provided the amount is enough for conducting thehydrosilylation reaction to a sufficient degree. When the platinumcatalyst is used as the component (iii), in general, a preferred amountof blending the component (iii) is in a range of from 0.1 to 1000 ppmcalculated as the amount of platinum with respect to the total amount ofthe components (i), (ii) and the component (v) that is blended asrequired.

The amount of the filler which is the component (iv) is adjusted at anytime depending upon the properties (hardness, tensile strength, tearingstrength, etc.) required for the set product that is obtained by settingthe settable composition. Generally, however, it is desired that thefiller which is the component (iv) is blended in an amount of from 1 to30% by weight with respect to the total amount of the settablecomposition.

The settable composition for the silicone rubber lining materials isusually used in compliance with the so-called two-liquid mixing method.That is, the material A containing the setting catalyst and the materialB without containing the setting catalyst (both of these materials arein the form of a liquid or a paste) are separately prepared andpreserved. Just before the use, they are mixed together and are used forbeing set.

Here, the mixed material of the settable composition has a problem inthe handling thereof; i.e., its viscosity is low at first and easilydrips, so that applying the mixed one onto the denture becomesdifficult. This tendency becomes more conspicuous in the case of thecurable composition for obtaining a lining material for the tissueconditioner that requires a high degree of flexibility. If the mixedmaterial easily drips, for example, the mixed material applied on theedges of the denture base flows out at the time of curing the curablecomposition (mixed material) in the oral cavity of a patient. As aresult, the lining material obtained by the setting of the mixedmaterial fails to assume a round shape which is necessary for thedenture to be strongly adhered in the oral cavity.

In this case, blending a liquid polyether into the settable compositionis effective for preventing the dripping while suppressing the viscosityof the mixed material of the curable composition. As the liquidpolyether, there can be used any known compound which is in the liquidstate or in the viscous state exhibiting at least fluidity at 25° C. ina single kind or in a combination of two or more kinds provided it doesnot impair the curing reaction of the organopolysiloxane.

What can be favorably used as the liquid polyether is a polyether havingan alkylene oxide group as a repeating unit. As the alkylene oxidegroup, it is desired to use the one having a straight chain or branchedchain alkylene group with 2 to 4 carbon atoms. For example, there can bepreferably used polyalkylene glycols such as polyethylene glycol,polypropylene glycol, and polybutylene glycol; and polyethers in whichthe polyalkylene glycol is ether-bonded to the hydroxyl group of theglycerin. Among them, it is desired to use a polyalkylene glycol fromthe standpoint of its high drip-preventing effect and biocompatibility.It is desired to use a polyethylene glycol having a molecular weight offrom 200 to 600 and, most desirably, to use a polypropylene glycolhaving a molecular weight of from 400 to 3500.

It is desired that the liquid polyether is blended in an amount of from0.01 to 5% by weight and, particularly, from 0.03 to 3% by weight withrespect to the total amount of the settable composition (total amount ofthe materials A and B inclusive of the liquid polyether). Even when theblending amount is greater than the above range, there is no improvementin the effect for preventing the dripping causing a disadvantage ineconomy. When the blending amount is smaller than the above range, onthe other hand, the effect is not enough for preventing the dripping.The liquid polyether may be added to either the above material A or thematerial B, or to both the materials A and B, or may further be added atthe time of mixing the materials A and B together.

It is further allowable to add a variety of fillers and a variety ofadditives to the curable composition for the silicone rubber liningmaterials in addition to those described above within a range in whichthey will not impair the properties of the cured product.

Kit for Lining

According to a preferred embodiment of the present invention, theadhesive for the silicone rubber lining materials is realized as a kitfor lining the (meth)acrylic resin denture base in combination with theabove-mentioned settable composition for the silicone rubber liningmaterial.

The adhesive of the present invention is capable of firmly adhering thesilicone rubber lining material to the (meth)acrylic resin of thedenture base within short periods of time simultaneously with thesetting of the settable composition for the silicone rubber liningmaterial based on the hydrosilylation reaction. Though the mechanism ofadhesion has not been clarified yet, the present inventors speculate itas described below.

Namely, the organic solvent in the adhesive causes the (meth)acrylicresin of denture base to swell, wherein the resin is impregnated withthe poly(meth)acrylate portion of the reactive siloxane-modified(meth)acrylic polymer (component (b)) in the adhesive inducing molecularentanglement of the poly(meth)acrylate chain. The siloxane portionhaving a functional group reactive in the hydrosilylation reaction, onthe other hand, emerges on the surface of the adhesive layer. Here, ifthe silicone paste (settable composition for the silicone rubber liningmaterial) which is settable upon the hydrosilylation reaction, isapplying thereon, they become very compatible with each other because ofthe same siloxane and, besides, a point of double bond reaction in thesilicone paste reacts with the functional group, which is reactive inthe hydrosilylation reaction, in the reactive siloxane-modified(meth)acrylic polymer. It is therefore considered that the (meth)acrylicresin of denture base and the adhesive layer firmly adhere together, andthe adhesive layer and the silicone rubber lining material firmly adheretogether.

As for the mechanism of greatly improving the durability of adhesion dueto the presence of the (meth)acrylic acid lower alkyl ester polymer inthe adhesive, the inventors speculate it as described below.

That is, the (meth)acrylic acid lower alkyl ester polymer which is thecomponent (c) has a property of easily and molecularly entangling withthe (meth)acrylic resin of denture base. Therefore, addition of theabove polymer further assists the molecular entanglement of the(meth)acrylate chain in the adhesive layer with the (meth)acrylic resinof denture base, contributing to enhancing the durability of adhesion.

In general, further, the (meth)acrylic resin is less impregnated with ahalogen-free organic solvent than with a halogen-containing organicsolvent. Therefore, use of the halogen-free organic solvent as anorganic solvent for the adhesive leaves the molecular entanglement smallbetween the (meth)acrylic resin of denture base and thepoly(meth)acrylate chain in the adhesive layer. Therefore, thedurability of adhesion is low. By being blended with the (meth)acrylicacid lower alkyl ester polymer as described above, however, theabove-mentioned phenomenon is improved and the effect of the inventionis exhibited more conspicuously.

As described above, the adhesive for the silicone rubber lining materialof the present invention is capable of firmly adhering the (meth)acrylicresin of denture base and the lining material together, and the adheringperformance is not only such that the adhering force is high in theinitial period but also that the durability of adhesion is excellentlymaintained.

When the organic solvent in the adhesive is a halogen-free organicsolvent such as ethyl acetate, the durability of adhesion decreasesgreatly. According to the present invention, however, the above effectis exhibited very favorably even when the organic solvent is thehalogen-free organic solvent. Thus, the present invention offers a lowlytoxic adhesive without using halogen-containing organic solvent whichinvolves problems in regard to safety.

EXAMPLES

The invention will now be concretely described by way of Examples towhich only, however, the invention is in no way limited.

Described below are the materials used for the tests.

(a) Halogen-free Organic Solvents:

-   -   Ethyl acetate (Wako Junyaku Co., special grade)    -   Acetone (Wako Junyaku Co., special grade)    -   Heptane (Wako Junyaku Co., special grade)    -   Diethyl ether (Wako Junyaku Co., special grade, abbreviated as        ether)        (b) Reactive Siloxane-modified (Meth)acrylic Polymer

The following copolymers were used.

The above copolymers were synthesized by the methods described below.

Structures of the starting hydrogen siloxane compounds used for thesynthesis of the copolymers are shown in Table 1 below.

TABLE 1 Co- Starting hydrogen polymer siloxane compound Abbreviation{circle around (1)} {circle around (3)} {circle around (4)}

DMS-M20H20: Shin-etsu kagaku {circle around (2)}

DMS- M10H10P10 {circle around (5)}

DHS-M20H20Synthesis of the Copolymer {circle around (1)}:

Into a flask were introduced 25 g of a methyl methacrylate, 0.63 g of anallyl methacrylate, 0.26 g of an azobisisobutyronitrile and 30 ml oftoluene, which were, then, heated at 70° C. with stirring while beingbubbled with nitrogen to obtain a copolymer (weight average molecularweight of 120,000) having a copolymer ratio of the methyl methacrylateand the allyl methacrylate of 50 to 1 (molar ratio).

Into a flask were introduced 27.7 g of a hydrogen siloxane compoundDMS-M20H20 shown in Table 1, 300 ml of toluene and 0.33 g of aplatinum/divinylsiloxane complex solution adjusted to 1000 ppm ofplatinum, which were, then, heated at 80° C. with stirring while beingbubbled with nitrogen. 5 g of the copolymer (weight average molecularweight of 120,000) having a copolymer ratio of the methyl methacrylateand the allyl methacrylate of 50 to 1 (molar ratio) synthesized by theabove method, was dissolved in 100 ml of toluene, which was then addedthereto dropwise. After the dropwise addition has been finished, themixture was heated and stirred for 6 hours. After the toluene wasremoved under reduced pressure, the excess of DMS-M20H20 was washed witha methanol/ethanol mixed solvent, separated by filtration and was driedto obtain the copolymer {circle around (1)}. The obtained polymerpossessed a weight average molecular weight of 180,000 (calibrated withpolystyrene).

Synthesis of the Copolymer {circle around (2)}:

Into a flask were introduced 25 g of a methyl methacrylate, 0.63 g of anallyl methacrylate, 0.40 g of an azobisisobutyronitrile and 30 ml oftoluene, which were, then, heated at 70° C. with stirring while beingbubbled with nitrogen to obtain a copolymer (weight average molecularweight of 80,000) having a copolymer ratio of the methyl methacrylateand the allyl methacrylate of 50 to 1 (molar ratio).

A copolymer {circle around (2)} was obtained by synthesizing a hydrogensiloxane compound DMS-M10H10P10 shown in Table 1 and the copolymer(weight-average molecular weight of 80,000) having a copolymer ratio ofthe methyl methacrylate and the allyl methacrylate of 50 to 1 (molarratio) in the same manner as the synthesis of the copolymer {circlearound (1)}.

Synthesis of the Copolymer {circle around (3)}:

Into a flask were introduced 25 g of a methyl methacrylate, 1.30 g of amethacrylic acid triethylene glycol monoarylether ester, 0.31 g of anazobisisobutyronitrile and 30 ml of toluene, which were, then, heated at70° C. with stirring while being bubbled with nitrogen to obtain acopolymer (weight-average molecular weight of 100,000) having acopolymer ratio of the methyl methacrylate and the allyl methacrylate of50 to 1 (molar ratio).

A copolymer {circle around (3)} was obtained by synthesizing a hydrogensiloxane compound DMS-M20H20 shown in Table 1 and the copolymer(weight-average molecular weight of 100,000) having a copolymer ratio ofthe methyl methacrylate and the allyl methacrylate of 50 to 1 (molarratio) in the same manner as the synthesis of the copolymer {circlearound (1)}.

Synthesis of the Copolymer {circle around (4)}:

Into a flask were introduced 25 g of a methyl methacrylate, 1.1 g of anallyl methacrylate, 0.57 g of an azobisisobutyronitrile and 30 ml oftoluene, which were, then, heated at 70° C. with stirring while beingbubbled with nitrogen to obtain a copolymer (weight-average molecularweight of 60,000) having a copolymer ratio of the methyl methacrylateand the allyl methacrylate of 57 to 2 (molar ratio).

A copolymer {circle around (4)} was obtained by synthesizing thehydrogen siloxane compound DMS-M20H20 and the copolymer (weight averagemolecular weight of 80,000) having a copolymer ratio of the methylmethacrylate and the allyl methacrylate of 57 to 2 (molar ratio) in thesame manner as the synthesis of the copolymer {circle around (1)}.

Synthesis of the Copolymer {circle around (5)}:

A copolymer {circle around (5)} was obtained by synthesizing thehydrogen siloxane compound DMS-M20H20 shown in Table 1 and the copolymer(weight average molecular weight of 100,000) having a copolymer ratio ofthe methyl methacrylate and the allyl methacrylate of 50 to 1 (molarratio) obtained in the synthesis of the copolymer {circle around (3)},in the same manner as the synthesis of the copolymer {circle around(1)}.

Synthesis of the Copolymer {circle around (6)}:

Into a flask were introduced 25 g of a methyl methacrylate, 2.3 g of asiloxane compound of the following formula,

0.26 g of an azobisisobutyronitrile and 30 ml of toluene, which were,then, heated at 80° C. for 5 hours with stirring while being bubbledwith nitrogen to obtain a copolymer {circle around (6)}.(c) (Meth) Acrylic Acid Lower Alkyl Ester Polymer:

-   -   Polymethyl methacrylate (PMMA)        -   D250 ML (molecular weight, 250,000, Sekisui Kasei Co.)        -   MB100 (molecular weight, 800,000, Sekisui Kasei Co.)    -   Methyl methacrylate/ethyl methacrylate copolymer {P(MMA-EMA)}        -   MBE10-110 (copolymer ratio: EMA/MMA=10/90,        -   molecular weight, 250,000, Sekisui Kasei Co.)        -   MBE70-55 L (copolymer ratio: EMA/MMA=70/30,        -   molecular weight, 250,000, Sekisui Kasei Co.)    -   Polyethyl methacrylate (PEMA)        -   EMA35 (molecular weight, 500,000, Sekisui Kasei Co.)

In the following Examples and Comparative Examples, the addition-typesilicone rubber used for the measurement of adhering strength was theone obtained by mixing the pastes A1 and A2, on the pasts B1 and B2 eachin an equal amount followed by setting.

Paste A1:

-   -   Polydivinyldimethyl siloxane        -   ME91, Toshiba Silicone Co., 50 parts by weight    -   Polydivinyldimethyl siloxane        -   XC86-A9723, Toshiba Silicone Co., 50 parts by weight    -   Platinum/vinyl siloxane complex solution (platinum, 1000 ppm,        Pt/V2), 0.3 parts by weight    -   Fine polymethylsilsesqueoxane particles (particle size, 3 μm,        obtained by the hydrolysis of a    -   methyltrimethoxysilane), 40 parts by weight        Paste A2:    -   Polydivinyldimethyl siloxane        -   ME91, Toshiba Silicone Co., 50 parts by weight    -   Polydivinyldimethyl siloxane        -   XC86-A9723, Toshiba Silicone Co., 50 parts by weight    -   Polyhydrogenmethyl siloxane        -   DMS-M20H20, Shin-etsu Kagaku Co., 2 parts by weight        -   TSL9586, Toshiba Silicone Co., 7 parts by weight

The silicone rubber obtained by mixing the above pastes A1 and A2 eachin an equal amount followed by setting exhibited a tensile strength ofabout 2.0 MPa.

Paste B1:

-   -   Polydivinyldimethyl siloxane        -   ME91, Toshiba Silicone Co., 60 parts by weight    -   Polydivinyldimethyl siloxane        -   XC86-A9723, Toshiba Silicone Co., 40 parts by weight    -   Platinum/vinyl siloxane complex solution (platinum, 1000 ppm,        Pt/V2), 0.3 parts by weight    -   Silica powder (primary particle size, 0.01 μm,    -   Reolosil MT-10, Tokuyama Co.), 10 parts by weight    -   Polypropylene glycol (molecular weight, 3000, Wako Junyaku Co.),        0.1 part by weight        Paste B2:    -   Polydivinyldimethyl siloxane        -   ME91, Toshiba Silicone Co., 40 parts by weight    -   Polydivinyldimethyl siloxane        -   XC86-A9723, Toshiba Silicone Co., 60 parts by weight    -   Polyhydrogenmethyl siloxane        -   DMS-M20H20, Shin-etsu Kagaku Co., 3 parts by weight    -   Silica powder (Reolosil MT-10, Tokuyama Co.), 10 parts by weight    -   Polypropylene glycol (Wako Junyaku Co.), 0.1 part by weight

The silicone rubber obtained by mixing the above pastes B1 and B2 eachin an equal amount followed by setting exhibited a tensile strength ofabout 2 MPa.

Evaluation of adhering force and durability of adhesion, procedure formeasurement, and the reference of evaluation were as described below.

(a) Evaluating the Adhering Force.

The adhesive solution prepared above was applied onto an acrylic plate(Acron GC) of which the surface was polished by using a water resistantpolishing paper, #800, while pouring water thereon. The two pastes A1and A2 or the two pastes B1 and B2 were taken each in an equal amount,mixed together well, and the mixed paste was applying on the acrylicplate on which the adhesive solution has been applied. The acrylic platewas left to stand at 25° C. for 10 minutes to cure the paste.

After setting, it was attempted to peel the acrylic plate and the setsilicone rubber from the interface thereof by using a spatula. Themanner of destruction at that moment was observed to evaluate theadhering force. The evaluation was rendered in four steps A to D incompliance with the following judgement:

-   -   A: Silicone rubber all underwent aggregation destruction        (adhering force>2.0 MPa).    -   B: Mixed destruction of aggregation destruction and interfacial        destruction (adhering force is nearly 2.0 MPa).    -   C: Interfacial destruction (adhering force<2.0 MPa).    -   D: Interfacial destruction (has not quite been adhered)        (adhering force is almost 0 MPa).        (b) Evaluating the Durability of Adhesion.

There were prepared five samples for measuring the adhering strengthafter having been immersed in water maintained at 37° C. for 24 hours.The samples were subjected to a heat cycle testing at 4° C. and 60° C.repeated 10,000 times by using a heat shock tester (manufactured byThomas Scientific Instrument Co.).

After put to the heat cycle testing, the samples were evaluated fortheir adhering force by the above method. The samples were evaluated tobe ⊚ when five pieces were all A, were evaluated to be ◯ when fourpieces were A and one piece was B, were evaluated to be Δ when two ormore pieces were B and the remaining pieces were A, and were evaluatedto be X when there were contained the pieces of C and D.

Example 1

To 100 parts by weight of an ethyl acetate (organic solvent) were added1.5 parts by weight of a reactive siloxane-modified (meth)acryliccopolymer (copolymer {circle around (1)}) and 1.5 parts by weight of a(meth)acrylic acid lower alkyl ester polymer (D250 ML) to prepare anadhesive in the form of a solution of the present invention for siliconerubber lining materials.

As the addition-type silicone rubber, there were used the pastes A1 andA1.

By using the thus prepared adhesive, five pieces of the samples wereevaluated for their adhering forces to find good initial adhering forcesand good durability of adhesion as shown in Table 2.

Examples 2 to 17

Adhesives for the silicone rubber lining materials were prepared in thesame manner as in Example 1 but using the compositions shown in Table 2,and were evaluated for their adhering forces and durability of adhesion.Good initial adhering force and good durability of adhesion wereobtained no matter which adhesive was used for the silicone rubberlining material.

Comparative Example 1

A sample was prepared in the same manner as in Example 1 but using noadhesive for the silicone rubber lining material, and was evaluated forits adhering force and durability of adhesion. The result were as shownin Table 2. Quite no adhesion was accomplished in the initial stage andthe durability testing could not be conducted.

Comparative Examples 2 to 8

Adhesives for the silicone rubber lining materials were prepared withoutadding the (meth)acrylic acid lower alkyl ester polymer but using thecompounds shown in Table 2 instead of using the reactivesiloxane-modified (meth)acrylic polymer, and were evaluated for theiradhering forces and durability of adhesion in the same manner as inExample 1. The results were as shown in Table 2.

The initial adhering forces were good, but the durability of adhesionhad been decreased to a conspicuous degree.

Comparative Examples 9 to 11

The adhering forces and durability of adhesion were evaluated in thesame manner as in Example 1 by using copolymers {circle around (7)},{circle around (8)} and {circle around (9)} having the followingstructures instead of using the (meth)acrylic acid lower alkyl esterpolymer. The results were as shown in Table 2.

The initial adhering forces were good but the durability of adhesion wasvery poor.

Comparative Example 12

An adhesive for the silicone rubber lining material prepared withoutadding the reactive siloxane-modified (meth)acrylic polymer wasevaluated for its adhesive force and durability of adhesion in the samemanner as in Example 1. The results were as shown in Table 2.

Quite no adhesion was accomplished in the initial stage and thedurability of adhesion could not be evaluated.

Comparative Example 13

As an example in which the blending amount of the (meth)acrylic acidlower alkyl ester polymer was smaller than the amount specified by thepresent invention, an adhesive for the silicone rubber lining materialprepared by using the composition shown in Table 1 was evaluated for itsadhering force and durability of adhesion in the same manner as inExample 1. The results were as shown in Table 2.

The initial adhering force was good but the durability of adhesion wasvery poor.

Comparative Example 14

An adhesive for the silicone rubber lining material prepared withoutadding the (meth)acrylic acid lower alkyl ester polymer but using theacetone as an organic solvent, was evaluated for its adhering force andthe durability of adhesion in the same manner as in Example 1. Theresults were as shown in Table 2.

The initial adhering force was good but the durability of adhesion wasvery poor.

Comparative Example 15

An adhesive for the silicone rubber lining material prepared withoutadding the (meth)acrylic acid lower alkyl ester polymer but using themethylene chloride as an organic solvent, was evaluated for its adheringforce and the durability of adhesion in the same manner as in Example 1.The results were as shown in Table 2.

The initial adhering force was good and the durability of adhesion wasrelatvely good but was slightly inferior to that of Example 1.

Examples 18 to 22

Adhesives for the silicone rubber lining materials were prepared in thesame manner as in Example 1 but by using the pastes B1 and B2 as theaddition-type silicone rubber, and were evaluated for their adheringforces and durability of adhesion. The results were as shown in Table 2.Good initial adhering forces and durability of adhesion were obtained nomatter which adhesive was used for the silicon rubber lining material.

TABLE 2 adhering Siloxane non-modified Siloxane modified force polymercopolymer after Concen- Concen- Adher- heat tration/ tration/ ing shockDura- Solvent Kind wt. parts Kind wt. parts force test bility Ex.1 ethylacetate D250ML 1.5 copolymer {circle around (1)} 1.5 AAAAA AAAAA ⊚ Ex.2ethyl acetate MB100 1.5 copolymor {circle around (1)} 1.5 AAAAA AAAAA ⊚Ex.3 ethyl acetate MBE10-110 1.5 copolymer {circle around (1)} 1.5 AAAAAAAAAA ⊚ Ex.4 ethyl acetate MBE70-55L 1.5 copolymer {circle around (1)}1.5 AAAAA AAAAA ⊚ Ex.5 ethyl acetate EMA35 1.5 copolymer {circle around(1)} 1.5 AAAAA AAAAA ⊚ Ex.6 ethyl acetate EMA35 0.3 copolymer {circlearound (1)} 1.5 AAAAA AAAAA ⊚ Ex.7 ethyl acetate EMA35 4.0 copolymer{circle around (1)} 4.0 AAAAA AAAAA ⊚ Ex.8 ethyl acetate EMA35 10.0 copolymer {circle around (1)} 2.0 AAAAA AAAAA ⊚ Ex.9 ethyl acetate EMA351.5 copolymer {circle around (2)} 1.5 AAAAA AAAAA ⊚ Ex.10 ethyl acetateEMA35 1.5 copolymer {circle around (3)} 1.5 AAAAA AAAAA ⊚ Ex.11 ethylacetate EMA35 1.5 copolymer {circle around (4)} 1.5 AAAAA AAAAA ⊚ Ex.12ethyl acetate EMA35 1.5 copolymer {circle around (5)} 1.5 AAAAA AAAAA ⊚Ex.13 ethyl acetate EMA35 1.5 copolymer {circle around (6)} 1.5 AAAAAAAAAA ⊚ Ex.14 ether EMA35 1.5 copolymer {circle around (1)} 1.5 AAAAAAAAAB ◯ Ex.15 ethylmethyl ketone EMA35 1.5 copolymer {circle around (1)}1.5 AAAAA AAAAB ◯ Ex.16 acetone EMA35 1.5 copolymer {circle around (1)}1.5 AAAAA AAAAB ◯ Ex.17 ethyl acetate/ EMA35 1.5 copolymer {circlearound (1)} 1.5 AAAAA AAAAB ◯ acetone (80/20) Ex.18 ethyl acetate EMA351.5 copolymer {circle around (1)} 1.5 AAAAA AAAAA ⊚ Ex.19 ethyl acetateEMA35 0.3 copolymer {circle around (1)} 1.5 AAAAA AAAAA ⊚ Ex.20 ethylacetate EMA35 10.0  copolymer {circle around (1)} 2.0 AAAAA AAAAA ⊚Ex.21 ethyl acetate MBE10-110 1.5 copolymer {circle around (1)} 1.5AAAAA AAAAA ⊚ Ex.22 ethyl acetate EMA35 1.5 copolymer {circle around(4)} 1.5 AAAAA AAAAA ⊚ Comp.Ex.1 — — — — — DDDDD — X Comp.Ex.2 ethylacetate — — copolymer {circle around (1)} 1.5 AAAAA BCCCC X Comp.Ex.3ethyl acetate — — copolymer {circle around (2)} 1.5 AAAAA BBCCC XComp.Ex.4 ethyl acetate — — copolymer {circle around (3)} 1.5 AAAAABBCCC X Comp.Ex.5 ethyl acetate — — copolymer {circle around (4)} 1.5AAAAA BCCCC X Comp.Ex.6 ethyl acetate — — copolymer {circle around (5)}1.5 AAAAA BCCCC X Comp.Ex.7 ethyl acetate — — copolymer {circle around(6)} 1.5 AAAAA BBBCC X Comp.Ex.8 ethyl acetate — — copolymer {circlearound (1)} 4.0 AAAAA BBCCC X Comp.Ex.9 ethyl acetate copolymer {circlearound (7)} 1.5 copolymer {circle around (1)} 1.5 AAAAA BBCCC XComp.Ex.10 ethyl acetate copolymer {circle around (8)} 1.5 copolymer{circle around (1)} 1.5 AAAAA BCCCC X Comp.Ex.11 ethyl acetate polymer{circle around (9)} 1.5 copolymer {circle around (1)} 1.5 AAAAA BBBCC XComp.Ex.12 ethyl acetate EMA35 1.5 — — DDDDD — X Comp.Ex.13 ethylacetate EMA35  0.05 copolymer {circle around (1)} 1.5 AAAAA BBBBC XComp.Ex.14 acetone copolymer {circle around (1)} 1.5 AAAAA CCCCC XComp.Ex.15 methylene — — copolymer {circle around (1)} 1.5 AAAAA AAABB ◯chloride

1. An adhesive for silicone rubber lining materials, for adhering asilicone rubber lining material and a (meth)acrylic resin denture basetogether, comprising: (a) 100 parts by weight of an organic solvent; (b)0.1 to 20 parts by weight of a (meth)acrylic polymer modified with asiloxane having a functional group reactive in the hydrosilylationreaction; and (c) 0.1 to 20 parts by weight of a polymer of a(meth)acrylic acid alkyl ester represented by the following formula,CH₂═C(X)—COOR wherein X is a hydrogen atom or a methyl group, and R isan alkyl group having 1 to 6 carbon atoms.
 2. An adhesive for siliconerubber lining materials according to claim 1, wherein the (meth)acrylicresin polymer which is the component (b) contains structural units (α)represented by the following formula (1) in an amount of from 10 to99.9% by mol, structural units (β) represented by the following formulas(2) and/or (2′) in an amount of from 90 to 0.1% by mol, and structuralunits (γ) represented by the following formula (3) in an amount of from0 to 89.9% by mol, and has a weight-average molecular weight of from5,000 to 1,000,000,

wherein, in the above formulas (1), (2), (2′) and (3): R¹, R² and R¹³are a hydrogen atom, a methyl group or an ethyl group; R³ is an alkylgroup having 1 to 13 carbon atoms or an aryl group having 6 to 14 carbonatoms; R⁴ to R¹⁰ and R¹⁵ to R²¹ are an alkyl group having 1 to 6 carbonatoms or an aryl group having 6 to 14 carbon atoms; R¹¹, R¹² and R²² area hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an arylgroup having 6 to 14 carbon atoms; R¹⁴ is an unsaturated hydrocarbongroup having 2 to 20 carbon atoms, which may have an ether bond or anester bond in the main chain thereof; A is a divalent hydrocarbon grouphaving 2 to 20 carbon atoms, which may have an ether bond or an esterbond in the main chain thereof; c and d are the average number ofrepeating units of silicone, c being a number of from 1 to 100 and dbeing a number of from 0 to 100, and wherein 10≦c+d≦100 and 0≦d/c≦10. 3.An adhesive for silicone rubber lining materials according to claim 1,wherein the organic solvent which is the component (a) is a halogen-freeorganic solvent.
 4. An adhesive for silicone rubber lining materialsaccording to claim 3, wherein the halogen-free organic solvent is ethylacetate.
 5. A kit for lining a (meth)acrylic resin denture basecomprising (I) a setting composition for silicone rubber liningmaterials, and (II) the adhesive for the silicone rubber liningmaterials of claim
 1. 6. A kit for lining a (meth)acrylic resin denturebase according to claim 5, wherein the settable composition for siliconerubber lining materials, which is the component (I) contains: (i) anorganopolysiloxane having at least two organic groups in the molecules,the organic groups having a carbon-carbon unsaturated bond at theterminals; (ii) an organohydrogenpolysiloxane having at least three SiHgroups in the molecules; (iii) a hydrosilylation catalyst; and (iv) asettable composition containing a silicone resin filler material and/ora silica filler.
 7. A kit for lining a (meth)acrylic resin denture baseaccording to claim 6, wherein the settable composition for siliconerubber lining materials, which is the component (I), further contains(v) an organohydrogenpolysiloxane having one or two SiH groups in themolecules thereof.
 8. A method of adhering a silicone rubber liningmaterial and a (meth)acrylic resin denture base together by adhering thesilicone rubber lining material and the (meth)acrylic resin denture basetogether by using the adhesive for silicone rubber lining materials ofclaim 1.